pinctrl: core: comment that pinctrl_add_gpio_range() is deprecated

The pinctrl_add_gpio_range() function is deprecated add a comment so
people don't accidentally use it in new code.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/533a7a10-c6eb-4ebe-adf1-f8dc95ae8d33@moroto.mountainSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -412,6 +412,10 @@ static int pinctrl_get_device_gpio_range(struct gpio_chip *gc,
  * @pctldev: pin controller device to add the range to
  * @range: the GPIO range to add
  *
+ * DEPRECATED: Don't use this function in new code.  See section 2 of
+ * Documentation/devicetree/bindings/gpio/gpio.txt on how to bind pinctrl and
+ * gpio drivers.
+ *
  * This adds a range of GPIOs to be handled by a certain pin controller. Call
  * this to register handled ranges after registering your pin controller.
  */